Three-Dimensional-Printed GelMA-KerMA Composite Patches as an Innovative Platform for Potential Tissue Engineering of Tympanic Membrane Perforations.

Tympanic membrane (TM) perforations, primarily induced by middle ear infections, the introduction of foreign objects into the ear, and acoustic trauma, lead to hearing abnormalities and ear infections. We describe the design and fabrication of a novel composite patch containing photocrosslinkable gelatin methacryloyl (GelMA) and keratin methacryloyl (KerMA) hydrogels. GelMA-KerMA patches containing conical microneedles in their design were developed using the digital light processing (DLP) 3D printing approach. Following this, the patches were biofunctionalized by applying a coaxial coating with PVA nanoparticles loaded with gentamicin (GEN) and fibroblast growth factor (FGF-2) with the Electrohydrodynamic Atomization (EHDA) method. The developed nanoparticle-coated 3D-printed patches were evaluated in terms of their chemical, morphological, mechanical, swelling, and degradation behavior. In addition, the GEN and FGF-2 release profiles, antimicrobial properties, and biocompatibility of the patches were examined in vitro. The morphological assessment verified the successful fabrication and nanoparticle coating of the 3D-printed GelMA-KerMA patches. The outcomes of antibacterial tests demonstrated that GEN@PVA/GelMA-KerMA patches exhibited substantial antibacterial efficacy against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Furthermore, cell culture studies revealed that GelMA-KerMA patches were biocompatible with human adipose-derived mesenchymal stem cells (hADMSC) and supported cell attachment and proliferation without any cytotoxicity. These findings indicated that biofunctional 3D-printed GelMA-KerMA patches have the potential to be a promising therapeutic approach for addressing TM perforations.

The Use of Infrapatellar Fat Pad-Derived Mesenchymal Stem Cells in Articular Cartilage Regeneration: A Review.

Cartilage is frequently damaged with a limited capacity for repair. Current treatment strategies are insufficient as they form fibrocartilage as opposed to hyaline cartilage, and do not prevent the progression of degenerative changes. There is increasing interest in the use of autologous mesenchymal stem cells (MSC) for tissue regeneration. MSCs that are used to treat articular cartilage defects must not only present a robust cartilaginous production capacity, but they also must not cause morbidity at the harvest site. In addition, they should be easy to isolate from the tissue and expand in culture without terminal differentiation. The source of MSCs is one of the most important factors that may affect treatment. The infrapatellar fat pad (IPFP) acts as an important reservoir for MSC and is located in the anterior compartment of the knee joint in the extra-synovial area. The IPFP is a rich source of MSCs, and in this review, we discuss studies that demonstrate that these cells have shown many advantages over other tissues in terms of ease of isolation, expansion, and chondrogenic differentiation. Future studies in articular cartilage repair strategies and suitable extraction as well as cell culture methods will extend the therapeutical application of IPFP-derived MSCs into additional orthopedic fields, such as osteoarthritis. This review provides the latest research concerning the use of IPFP-derived MSCs in the treatment of articular cartilage damage, providing critical information for the field to grow.

Tissue transglutaminase_variant 2-transduced mesenchymal stem cells and their chondrogenic potential.

As cartilage is incapable of self-healing upon severe degeneration because of the lack of blood vessels, cartilage tissue engineering is gaining importance in the treatment of cartilage defects. This study was designed to improve cartilage tissue regeneration by expressing tissue transglutaminase variant 2 (TGM2_v2) in mesenchymal stem cells (MSC) derived from bone marrow of rats. For this purpose, rat MSCs transduced with TGM2_v2 were grown and differentiated on three-dimensional polybutylene succinate (PBSu) and poly-l-lactide (PLLA) blend scaffolds. The transduced cells could not only successfully express the short form transglutaminase-2, but also deposited the protein onto the scaffolds. In addition, they could spontaneously produce cartilage-specific proteins without any chondrogenic induction, suggesting that TGM2_v2 expression provided the cells the ability of chondrogenic differentiation. PBSu:PLLA scaffolds loaded with TGM2_v2 expressing MSCs could be used in repair of articular cartilage defects.

Magnesium doping on TiN coatings affects mesenchymal stem cell differentiation and proliferation positively in a dose-dependent manner.

BACKGROUND: In vitro evaluation of cell-surface interactions for hard tissue implants have mostly been done using osteoblasts. However, when an implant is placed in the body, mesenchymal stem cells (MSCs) play a major role in new bone formation. Therefore, using MSCs in cell-surface investigations may provide more reliable information on the prediction of in vivo behavior of implants. OBJECTIVE: In this study, Mg doped TiN coatings ((Ti,Mg)N) were prepared and tested for their effect on MSC differentiation and mineralization. METHODS: MSCs were isolated from rat bone marrow (rBMSCs) and seeded onto bare Ti, TiN and Mg containing (Ti,Mg)N surfaces. Cell proliferation, osteogenic differentiation (collagen type 1, alkaline phosphatase activity), calcium phosphate deposition (von Kossa staining, Scanning Electron Microscopy) analysis were conducted. RESULTS: Differentiation towards osteoblast lineage was significantly improved with the increment in Mg presence. Collagen type I deposition, mineralization, and the ALP activity were higher on high Mg containing (>10 at% Mg) surfaces but differentiation of rBMSCs were found to be delayed. CONCLUSIONS: Mg presence affected rBMSCs proliferation and differentiation positively in a dose-dependent manner. However, high Mg amounts delayed both proliferation and differentiation.

Poly(amino acid)-based fibrous scaffolds modified with surface-pendant peptides for cartilage tissue engineering.

In this study, fibrous scaffolds based on poly(γ-benzyl-l-glutamate) (PBLG) were investigated in terms of the chondrogenic differentiation potential of human tooth germ stem cells (HTGSCs). Through the solution-assisted bonding of the fibres, fully connected scaffolds with pore sizes in the range 20-400 µm were prepared. Biomimetic modification of the PBLG scaffolds was achieved by a two-step reaction procedure: first, aminolysis of the PBLG fibres' surface layers was performed, which resulted in an increase in the hydrophilicity of the fibrous scaffolds after the introduction of N5 -hydroxyethyl-l-glutamine units; and second, modification with the short peptide sequence azidopentanoyl-GGGRGDSGGGY-NH2 , using the 'click' reaction on the previously modified scaffold with 2-propynyl side-chains, was performed. Radio-assay of the 125 I-labelled peptide was used to evaluate the RGD density in the fibrous scaffolds (which varied in the range 10-3 -10 pm/cm2 ). All the PBLG scaffolds, especially with density 90 ± 20 fm/cm2 and 200 ± 100 fm/cm2 RGD, were found to be potentially suitable for growth and chondrogenic differentiation of HTGSCs. Copyright © 2015 John Wiley & Sons, Ltd.

Behavior of mammalian cells on magnesium substituted bare and hydroxyapatite deposited (Ti,Mg)N coatings.

TiN and (Ti,Mg)N thin film coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition (arc-PVD) technique with magnesium contents of 0, 4.24 at% (low Mg) and 10.42 at% (high Mg). The presence of magnesium on both normal (hFOB) and cancer (SaOS-2) osteoblast cell behavior was investigated in (Ti,Mg)N surfaces with or without prior hydroxyapatite (HA) deposition (in simulated body fluid, SBF). Mg incorporation on TiN films was found to have no apparent effect on the cell proliferation in bare surfaces but cell spreading was better on low Mg content surface for hFOB cells. SaOS-2 cells, on the other hand, showed an increased extra cellular matrix (ECM) deposition on low Mg surfaces but ECM deposition almost disappeared when Mg content was increased above 10 at%. HA deposited surfaces with high Mg content was shown to cause a significant decrease in cell viability. While the cells were flattened, elongated and spread over the surface in contact with each other via cellular extensions on unmodified and low Mg doped surfaces, unhealthy morphologies of cells with round shape with a limited number of extended arms was visualized on high Mg containing samples. In summary, Mg incorporation into the TiN coatings by arc-PVD technique and successive HA deposition led to promising cell responses on low Mg content surfaces for a better osteointegration performance.